Catalytic hydrogenation with metal phosphate-containing catalysts

ABSTRACT

Aromatics hydrogenation process using a catalyst having a particle density greater than 1.4 g./cc., comprising alumina, a component selected from nickel and compounds thereof and cobalt and compounds thereof, a component selected from molybdenum and compounds thereof, and a component selected from titanium phosphate and zirconium phosphate.

Elite States Patent inventors James R. Kittrell El Cerrito; Richard C. Robinson, San Rafael, both of Calif. Appl. No. 862,036 Filed Sept. 29, 1969 Patented Dec. 14, 1971 Assignee Chevron Research Company San Francisco, Calif.

CATALYTIC HYDROGENATION WITH METAL PHOSPHATE-CONTATNING CATALYSTS 3 Claims, No Drawings US. Cl 208/143, 260/667, 252/437, 252/455 Int. Cl C07c 5/10, C 1 0g 23/02 Field 0! Search 208/143;

References Cited UNlTED STATES PATENTS Hass et al Ballard et a1 Vaell Jaffee Jaffee Primary Examiner-Herbert Levine Attorneys-A. L. Snow, F. E. Johnston, C. J. Tonkin and R. H.

Davies CATALYTIC IIYDROGENATION WITI-I METAL PHOSPHATE-CONTAINING CATALYSTS INTRODUCTION This application relates to hydrogenation of aromatic hydrocarbons.

PRIOR ART It is known that many hydrocarbon stocks such as jet fuels, kerosene, furnaces oils, lubricating oils, etc., can be upgraded by partial or completed hydrogenation of the aromatic constituents thereof.

Aromatic hydrogenation results in improved burning characteristics for many fuels. For example, in the case of jet fuels, desirably increases in smoke points can be obtained by hydrogenation of the aromatics contained in the fuels to the corresponding naphthenes, which have higher heats of combustion.

Commercial hydrofining processes directed to the removal of contaminants such as sulfur and nitrogen from hydrocarbon feedstocks inherently accomplish hydrogenation of olefin constituents of the feedstocks; however, these processes accomplish little or no hydrogenation or aromatics content in the feedstocks.

Aromatics hydrogenation processes are well known. Prior art hydrogenation catalysts generally comprise platinum on alumina, occasionally with a minor proportion of added halogen. Various other group Vlll metals, such as nickel, cobalt and iron, as well as other metals of the platinum group, deposited on alumina or other suitable carriers also have been employed. The prior art processes have been carried out at temperatures within the range 300 to 900 F pressures with in the range 1,9000 to 5,000 p.s.i.g., and liquid hourly space velocities in the range 0.1 to 20, in the presence of 2,500 to 25,000 standard cubic feet of hydrogen per barrel of changed material. Generally, low-catalyst densities are desirably for platinum hydrogenation catalysts of the prior art, as exemplified by U.S. Pat. No. 3,432,565.

Conventional aromatics hydrogenation processes are disclosed in the following representative U.S. Pat. Nos.

Conventional aromaticshydrogenation catalysts, particularly catalysts containing group VIII noble metals, are sulfursensitive, and the presence of organic sulfur compounds in the feed exerts a deleterious effect on the hydrogenation activity of these catalysts. The sulfur sensitivity of the group VIII noble metal hydrogenation catalysts is particularly discussed in the aforesaid U.S. Pats. Nos. 3,147,210 and 3,186,935.

In view of the importance of aromatics hydrogenation for improving the burning characteristics of man aromatics-containing hydrocarbon feedstocks, there is a continuing search for improved processes for accomplishing the desired hydrogenation, particularly processes using aromatics hydrogenation catalysts having higher aromatics hydrogenation activities and/or lower fouling rates, that is, higher stabilities.

OBJECTS In view of the foregoing, it is an object of the present invention to provide an improved aromatics hydrogenation process employing a catalyst of high-activity and stability which permits the process to be operated at reasonable temperatures for long periods of time. It is a further object of the present invention to provide an aromatics hydrogenation process using a catalyst which contains less costly constituents than the conventional group VIII noble metal hydrogenation catalysts, and which is more sulfur-tolerant than those conventional catalysts.

STATEMENT OF INVENTION In accordance with the present invention, there is provided an aromatics hydrogenation process which comprises contacting an aromatics-containing hydrocarbon feedstock under aromatics hydrogenation conditions with hydrogen and a catalyst comprising alumina, a component selected from nickel and compounds thereof and cobalt and compounds thereof, a component selected from molybdenum and compounds thereof and a component selected from titanium phosphate and zirconium phosphate, the particle density of said catalyst exceeding 1.4 g./cc. In preferred embodiment of the process of the present invention, the catalyst used therein contains 0.5 to 20 weight percent, preferably 0.5 to 5 weight percent, natural or synthetic clay, or natural or synthetic zeolite, based on the total catalyst. Specific calcination conditions can also achieve such particle densities.

The aromatics hydrogenation conditions used in the process of the present invention are conventional conditions as discussed below.

CATALYST ACTIVITIES The activity of any catalyst can be described by the rate constant of the reaction of a reference catalyst temperature.

FOr aromatics hydrogenation, said rate constant may be written:

A! e r .lifm. l i (r at. where k is the rate constant, LI'ISV is liquid hourly space velocity (note exact definitions in the following paragraph), A is the aromatic content of the feed, A is the aromatic content of the hydrogenated product, and A, is the aromatic content which would be obtained in the product had the reaction proceeded to equilibrium.

A variety of definitions for space velocities are usable in the above expression. Because of variations in reactor bed packing and the relation of the surface area, and therefore catalytically active sites to a weight of catalyst (usually given as square meters/gram the most significant space velocity is based on weight measures:

Feed rate, grams/hour (LHSY) "Ea ers? wei bk ia Feed rate, cc. hour J v Catalyst alurne, cc.

Therefore, a ranking of catalyst activities for commercial use must be calculated on volumetric space velocities.

If all catalysts exhibited the same bulk density when packed into a reactor, of course rankings of catalysts on these two bases would be fully equivalent. However, variation in catalyst preparations techniques can vary either the packing factor or the particle density of the catalysts, thus changing these rankings. For example, Kouwenhoven, et al. in U.S. Pat. No. 3,432,565 have demonstrated that low-density hydrogenation catalysts exhibit highest activities if the catalyst is comprised of group VIII metals on alumina. The present invention is directed to an aromatic hydrogenation process using a highdensity catalyst comprising alumina, a component selected from nickel and compounds thereof and cobalt and compounds thereof, a component selected from molybdenum and compounds thereof, and a component selected from titanium phosphate and zirconium phosphate.

FEEDSTOCKS Hydrocarbon feedstocks which may be used to advantage in the process of the present invention include and wide range of aromatics-containing hydrocarbon feedstocks, for example light and heavy straight run gas oils, light and heavy cracked cycle oils, and various aromatic extracts.

The hydrocarbon'feedstock will contain 5 to 95 percent preferably to 80 percent, aromatics.

Cracked stocks may be obtained from thermal or catalytic cracking of various stocks, including those obtained from petroleum, gilsonite, shale and coal tar.

The organic nitrogen and organic sulfur contents of the hydrocarbon feedstocks each may range from a few parts per million to several weight percent. If desired, the feedstocks may be treated in a conventional hydrofining step to reduce the sulfur and nitrogen contents thereof, prior to being hydrogenated in accordance with the process of the present invention.

HYDROGENATION CONDITIONS The process of the present invention may be carried out at conventional hydrogenation conditions, for example at a temperature in the range 400 to 900 F., a pressure in the range 500 'p.s.i.g., and a liquid hourly space velocity in the range 0.2 to 20, and in presence of 1,000 to 20,000 standard cubic feet of hydrogen per barrel of charged material.

The process of the present invention may be carried out at any desired combination of conditions within the foregoing ranges with produce a desired degree of aromatics hydrogenation. Desirably, a combination of conditions is selected which will result in hydrogenation of more than 50 volume percent and preferably more than 90 volume percent of the aromatics present in the feedstock.

CATALYST CONSTITUENTS AND'AMOUNTS THEREOF The catalyst used in the process of the present invention will contain the following constituents in the indicated amounts:

Wt. calculated as metal Ni or C0. generally as Nio or CoO l-lO Mo, generally as M00, 5-25 TiO, or ZrO, 5-20 r 3-!5 1 at least 20 Clay and/or zeolite 0-20 Additionally, the catalyst may contain combined fluorine, in an amount of 0-10 weight percent.

When the catalyst used in the process of the present invention contains titanium and no zirconium, the titanium: phosphate atomic ratio will be greater than 1:1. When the catalyst used in the process of the present invention contains zirconium and no titanium, the zirconiumzphosphate ratio will be greater than 1:2.

CATALYST PREPARATIONS The catalyst used in the process of the present invention conveniently may be prepared by such methods as impregnation of an alumina or silica-alumina support with salts of the desired hydrogenation component, or cogelation of all components, with the latter method being preferred. When the catalyst is cogelled, the necessary from for the catalyst used in the process of the present invention will be obtained, that is, one in which the titanium or zirconium is combined with the phosphorus as discrete particles of titanium phosphate or zirconium phosphate, dispersed through a carrier, or matrix, of the other catalyst components. The necessary high densities can be achieved by including in the catalyst a natural or synthetic clay, or a crystalline zeolitic molecular sieve, and/or by drying the cogel thoroughly and calcining the catalyst with high rates of dry air.

EXAMPLES The following examples will serve to further illustrate the practice of the present invention and its advantages.

EXAMPLE l A catalyst containing nickel, molybdenum, titanium, phosphorous, alumina and synthetic clay (catalyst A, a catalyst for use in the process of the present invention) was prepared by the following general procedure:

a. an aqueous solution comprising aluminum chloride,

titanium tetrachloride, and acetic acid was prepared;

b. titanium phosphate particles were caused to precipitate from said solution by combining said solution with a second aqueous solution containing phosphoric acid, resulting in a slurry containing said titanium phosphate particles;

c. an aqueous nickel chloride solution was added to said slurry to form a nickel-containing mixture;

d. aqueous solutions containing ammonia and ammonium molybdate were added to said mixture, to bring pH of the mixture to 4.0 to 4.5;

e. an aqueous slurry of synthetic clay (described in Granquist US. Pat. No. 3,252,757) was added to said mixture;

f. an aqueous solution containing ammonia was added to said mixture, causing further coprecipitation at a pH of 6 to 6.5 of soluble metals not previously precipitated;

g. the resulting slurry was filtered to produce a filter cake,

which was washed free of soluble ions;

h. the catalyst was aged 12 hours in a steam atmosphere, dried at 250 F. overnight, and calcined at a high rate of dry air at a terminal temperature of 950 F.

The particle density of the catalyst was 1.5 g./cc.

EXAMPLE 2 A catalyst containing nickel, molybdenum, titanium, phosphorus, fluoride and alumina (catalyst B, a catalyst for use in the process of the present invention) was prepared by the following general procedure:

a. an aqueous solution comprising aluminum chloride,

titanium tetrachloride, and acetic acid was prepared;

b. titanium phosphate particles were caused to precipitate from said solution by combining said solution with a second aqueous solution containing phosphoric acid, resulting in a slurry containing said titanium phosphate particles;

c. an aqueous nickel chloride solution was added to said slurry to form a nickel-containing mixture;

d. aqueous solutions containing ammonia, molybdic oxide and sodium hydroxide were added to said mixture, causing coprecipitation at a pH of 6 to 6.5 of soluble metals not previously precipitated;

e. ammonium fluoride was stirred into the mixture;

f. the resulting slurry was filtered to produce a filter cake,

which was washed free from soluble ions.

g. The catalyst was dried in flowing air at F. and calcined at a high rate of dry air at a terminal temperature of 950 F.

The particle density of the catalyst was 1.52 g./cc.

EXAMPLE 3 A low-density catalyst containing nickel, molybdenum, titanium, phosphorus and alumina (catalyst C, a comparison catalyst) was prepared by the following general procedure;

a. an aqueous solution comprising aluminum chloride,

titanium tetrachloride, and acetic acids was prepared;

b. titanium phosphate particles were caused to precipitate from said solution by combining said solution with a second aqueous solution containing phosphoric acid, resulting in a slurry containing said titanium phosphate particles;

c. an aqueous nickel chloride solution was added to said slurry to form a nickel-containing mixture;

d. aqueous solutions containing ammonia, molybdic oxide and sodium hydroxide were added to said mixture, caus- TABLE IL-HYDROGENA'IION OF AROMATICS IN LCD (60% AROMATICS CONTENT) ing coprecipitation at a pH of 6 to 6.5 of soluble metals Catalyst not previously precipitated; Catalyst LHSV LHSV. temp, F. A. A kw w e. the resulting slurry was filtered to produce a filter cake, 5 A 98 1. 7 v 0.99 1.07 700 1.5 18.1 1. 25 1.34 which was washed free of soluble ions, 1. 0O 1. 08 700 L 5 21, 5 0g 17 f. the catalyst was dried at 125 F. and calcined in a 1 pan with no airflow. The calcination was conducted by B 3% is; 3% $12 51 is: heating directly to 400 F. and holding 3 hours while added water at 100 cc./hour. The temperature was ad- O L04 L44 725 112 L42 L97 justed to 700 F. and then held 2.5 hours at 900 F. 1- 2 1- 725 7 0 93 The particle density of the catalyst was 1.18 g./cc. D L02 94 725 111 L24 1, 15 1.02 0.94 725 2.; EXAMPLE4 i 13; 3132 2 17 1114 1124 1:15 A catalyst containing nickel, tungsten, titanium, alumina 15 E L01 0'93 720 2.5 2&6 L02 L03 and silica, but no phosphorus (catalyst D, a comparison 11; u W a-.. em catalyst) was prepared by suitable modification of the general a procedure of example 1. The catalyst density was 1.74 g./cc. TABLE m NOMINAL ACTIVITIES AT 725 Activit Activit Particle EXAMPLE 5 20 (weigh: (volumi e Density A catalyst containing nickel, molybdenum and alumina has) has) (catalyst E, a comparison catalyst) was prepared by the following general procedure: Cmlys Present Invention a. an aqueous solution comprising aluminum chloride, Camp, A L75 L70 L50 nickel chloride and acetic acid was prepared; Catalyst 5 1.75 1.70 1.52 b. an aqueous solution of molybdic acid and concentrated I 75 l w I I8 hydrochloric 861d. was added; Cami D L74 c. an aqueous solution of ammonia was added to said mix- Catalyst E 1.00 1.00 1.10

ture to raise the pH to 7, causing coprecipitation of solu- It is apparent that catalysts A and B, catalysts of the present ble metals not previously precipitated; invention, have a hydrogenation activity substantially above d. the resulting slurry was filtered to produce a filter cake, that of the other catalysts of the above tabulation. Catalyst C which was washed free of soluble ions; had a composition which is appropriate, but is density and its e. the catalyst was dried at 100 F. and calcined in flowing activity on a volume basis are too low, since it was improperly air which had been saturated with water at 70 F., with a calcined. A change in the calcination procedure as discussed terminal calcination temperature of 950 F. herein will raise the density and bring the volumetric activity The particle density of the catalyst was 1.70 g./cc. The up to the 1.70 level of catalysts A and B. catalyst d, containing nominal compositions of the catalysts are shown in ta ble l. tungsten instead of molybdenum and without phosphorus pen- TABLE L-COMPOSITION 0F CATALYSTS N1 M0 W Clay F T10; P10; 810; A110;

The catalysts of examples 1-5 were used to hydrogenate separate portions of a California light-cycle oil of the following description:

Gravity. API 22.3 Aniline point, F. 61.2 Sulfur, wt. 17 1.27 Nitrogen. p.p.m. 2,140

Aromatic content. LVT; ASTM O-l I60 Distillation ST/S 394/459 l 0/3 0 475/504 5 0 527 70190 549/580 QSIEP 593/627 The hydrogenation was accomplished in a reactor under the following conditions:

Total Pressure. p.s.i.g. 2,000 Total hydrogen supply rate.

SCF/bbl. of hydrocarbon feed 5,000

Liquid hourly space velocity. V.Vlhour toxide, has low activity, even though the catalyst density is high, catalyst E, which does not contain titanium phosphate or zirconium phosphate, has sufficient density but still has low activity.

CONCLUSIONS From the foregoing it may be seen that the process of the present invention is effective for accomplishing a given amount of aromatics hydrogenation of a lower temperature than is possible with certain processes using different catalysts. It also may be seen that the process of the present invention is effective for accomplishing a greater amount of hydrogenation at a given temperature, for longer periods of time, than is possible with certain processes using different catalysts. It is further may be seen that the catalyst used in the process of the present invention. compared with the conventional prior art aromatics hydrogenation catalysts, does not require the use of costly group VIII noble metals, and is sulfurand nitrogen-tolerant.

What is claimed is:

1. An aromatics hydrogenation process which comprises 0 contacting an aromatics-containing hydrocarbon feedstock under aromatics hydrogenation conditions with hydrogen and a catalyst comprising alumina, 0.5 to 20 weight percent synthetic clay, a component selected from nickel and com- .pounds thereof and cobalt and compounds thereof, a component selected from molybdenum and compounds thereof, and a component selected from titanium phosphate and zirconium phosphate, said catalyst having a particle density greater than 1.4 g./cc., and said catalyst containing no noble metal and also containing no silica other than combined silica said synthetic clay. 

2. A process as in claim 1, wherein said catalyst has a bulk density greater than 1.5 g./cc.
 3. A process as in claim 1, wherein said feedstock contains sulfur in excess of 200 p.p.m. 